1. Field of the Invention
The present invention relates generally to golf club grips and more specifically to a golf club grip which is configured to improve the resistance to axial rotation of a golf club in a golfer's hands.
2. Description of the Prior Art
Axial rotation or twisting of a golf club in a golfer's hands is often a direct result of mis-hitting of a golf ball. Every golf club has what is referred to as a sweet spot which is located proximate the center of gravity of the golf club head. When a golfer hits a golf ball on, or near the sweet spot of the club, maximum distance and directional accuracy will result if all the other factors which enter into a golf swing are proper. When this ideal condition exists, little or no torsion force is applied to the golf club which would tend to cause it to twist, or rotate about the longitudinal axis of the golf club shaft. However, even the best golfers will miss the sweet spot sometimes and such mis-hits in a direction toward the toe or toward the heel of the club head will exert rotational forces which tend to cause the golf club to twist in the golfer's hands.
This tendency for twisting of golf clubs in the golfer's hands as a result of mis-hits of the type described above has been well known for a long time and especially designed golf club heads known as "perimeter weighted" golf clubs have come into widespread use to help off set this club twisting problem. It will be appreciated that golf club grips also are an important factor in counteracting the club twisting problem.
Several types and designs of golf club grips have been developed over the years. A grip which was at one time used extensively but is not as popular as it once was, is made by wrapping an elongated strip of leather about the upper end of the golf club shaft. A suitable adhesive, usually in the form of double-sided tape is used to attach this type of grip to the shaft.
By far the most widely used golf club grips today are those formed of a rubber composition by an injection molding process. These grips are of tubular frusto-conical configuration; i.e. tapered, and have a smaller diameter open lower end with its larger diameter upper end being closed by an integrally molded end cap. These rubber molded grips are slidably mounted in a coaxially disposed position on the upper extending end of the golf club shaft, and affixation is normally accomplished with a double-sided adhesive tape.
In recent years, grips molded of synthetic materials, such as silicone based compositions, have begun to appear in the marketplace. Such synthetic grips are similar in all respects to the rubber molded grips except for the materials of which they are made, and they are mounted and affixed on the ends of the golf club shafts in the same way.
One of the more important design objectives of golf club grips is to provided the golfer with maximum club gripping capability without requiring the application of excessive gripping pressure. To accomplish this objective, all of the materials of which golf club grips are made have some degree of tackiness, and the surfaces of the grips are porous or otherwise irregular to enhance the static friction exerting capabilities of the grip. The static friction exerting capability of golf club grips is further enhanced in the molded grips described above by providing those grips with a groove pattern. In addition to being decorative, such groove patterns act much like the tread patterns of automobile tires thus increasing the traction between the grip and a golfer's hands.
The static friction exertion capabilities of golf club grips are intended to counteract axial rotation, or twisting of the golf club as described above, and another undesirable type of movement which may be referred to as axial slippage. Axial slippage is movement in a direction coincident with the longitudinal axis of the golf club's shaft, and this movement results from centrifugal force acting on the golf club during a golf swing. On information and belief, all prior art golf club grips have their groove patterns arranged in a way so that they counteract both types of undesirable movements.
There are many different groove arrays with an exemplary pattern being in the form of a plurality of independent relatively short groove segments which are arranged to lie on 45.degree. angles relative to the longitudinal axis of the grip much like chevrons. This particular groove array has been used for many years on a well known and widely used grip known as a VICTORY Grip by Golf Pride. There are many variations of the chevron-like array used on other grips of Golf Pride and other manufacturers.
Another prior art grip used exclusively on PING Golf Clubs manufactured by Karsten Manufacturing Corporation is disclosed in U.S. Pat. No. Des. 281,991 issued on Dec. 31, 1985. The grooves molded on this particular grip are arranged to provide a plurality of independent squares each being disposed so that a diagonal of the square is parallel to the longitudinal axis of the grip.
Since the grooves of the prior art grips described above lie on 45 angles relative to the longitudinal axis of the grips, they are not disposed to be in direct opposition to either of the undesirable movements which they are intended to counteract. To most efficiently counteract axial slippage movements, the grooves should be arranged to lie in planes that are normal to the longitudinal axis of the grips. Similarly, to most efficiently counteract axial rotation, the grooves should be arranged parallel to the longitudinal axis of the grips.
Another type of prior art grip is disclosed in U.S. Pat. No. 254,926 issued on May 6, 1980. The grip of this patent has its grooves arranged to form independent squares that are disposed so that half of the grooves are in direct opposition to axial slippage movements; i.e. lie in planes normal to the longitudinal axis of the grips. The other half of the grooves are disposed to lie in direct opposition to axial rotation movements by being in parallel relationship to the longitudinal axis of the grip.
Another prior art golf club grip which is referred to as the "radial traction grip" by the Spalding Co. is provided with longitudinally extending grooves proximate the distal end of the grip. These longitudinally extending grooves are arranged in equally spaced circumferential increments about the grip and extend somewhat less then 1/3 the length of the grip from the distal end toward the proximal end. The remaining peripheral surface of this grip has angularly disposed grooves formed therein for counteracting the two types of unwanted golf club movement as hereinbefore described.
Still another prior art golf club grip is disclosed in U.S. Pat. No. 307,169 by J. S. Aldridge which issued on Apr. 10, 1990. The grip shown in this design patent is provided with longitudinal grooves which extend almost the full length of the grip. However, those grooves are arranged to lie in a sector defined by an inscribed angle of about 110.degree.. Thus, only slightly more than 1/4 of the peripheral surface of the grip of this design has the longitudinally extending grooves formed thereon. As in the prior art grip discussed immediately above, the remaining portions of this grip have angularly disposed grooves formed therein for counteracting the two types of previously described undesirable golf club movements.
It has been found that the undesirable movement hereinbefore defined as axial slippage is adequately counteracted by the inherent tackiness of the materials used in molding golf club grips, and the relatively large distal ends of the tapered grip. Thus, the added traction provided by the grooves is not needed to counteract axial slippage movements. Therefore, a need exists for a new and improved golf club grip wherein all of the grooves formed therein are disposed to counteract the undesirable movement of golf club grips which is defined herein as axial rotation.
A grip which was intended to answer this need is described in U.S. Pat. No. 5,087,042. However, as noted above, one of the design objectives of golf club grips is to provide a grip having the right "feel", or club gripping capability. The grip described in U.S. Pat. No. 5,087,042 was intended, as specifically stated in that patent, to "maximize" the static friction exertion capability of the portion of the grip which is gripped by the golfer's right hand (reference being made to a right handed golfer). This maximizing function was accomplished by providing first and second sets of longitudinal grooves in the grip, the first set running substantially the length of the grip and the second set running along the length of the grip only in that portion of the grip which is gripped by the right hand. In accordance with the golf swing "theory" espoused by that patent, the left hand of a right handed golfer should be the strong hand; that is, the one exerting the most influence on the golf club during the swing. This leaves the right hand as being relegated to a weaker position which ideally exerts a lesser amount of influence on the golf club during the swing (of course, with a left handed golfer, everything is reversed but the effect remains the same). The grip described in that patent was designed, therefore, to facilitate the gripping of the golf club grip in a manner consistent with that strong hand/weak hand golf swing theory, which was described in that patent as being a "widely accepted golf swing theory".
However, it is my belief that the better golf swing theory is the theory described by such teaching masters as Ben Hogan, who stated, at page 24 of his book entitled "5Lessons--The Modern Fundamentals of Golf" (1957), that "setting up a strong . . . left hand is one half of the job . . . , the other half, is getting your right hand in a position to perform its share of the work but not more that its equal share". It is clear, therefore, that there is a need for a golf club grip having the advantages of the grip described in U.S. Pat. No. 5,087,042 but which functions in a manner which is consistent with the school of golf instruction which teaches that the grip of both hands is equally important. For that reason, it is an object of the present invention to provide a golf club grip which equalizes the "grip", or static friction exertion capability, in the area of the grip which is gripped by both the right and left hands of the golfer.